I'm rereading the books, starting with Dragonsdawn (crap, but I'd forgotten how much that book makes me cry). I'm finding some discrepancies between the books and the Dragonlover's Guide to Pern (DLG), and I'm not sure which we should go with.

In the DLG, it's stated that Kitti Ping engineered the 5-finger claw for the front hand for the mentasynthed fire-dragonets. But in Dragonsdawn, it's clearly stated that the 5-finger claw was only added to the dragons, not the dragonets. This would mean that physically, there's no way to tell the difference between what they call a "menta" in Dragonsdawn and a genetically pure dragonet. Kitti was only attempting to make them more biddable at that time; they didn't know about Thread yet.

In addition, the popular name for fireliazards was "dragonets", Sean Connell was the only one who called them "lizards" (most people frowned on calling them such a rude name). There's no indication in the books, that I can recall at this point, that explained why they became known as firelizards later; but if I had to hazard a guess, I'd say it was because they wanted to refer to young dragons as "dragonets" and that just got confusing.

I like the 5 fingers, and I prefer fire lizards being fire lizards and dragons being dragons and dragonets when young. it has always confused me when other wise stated making it seem like there are 3 diffrent critters rather then just the 2.